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Exercise Changes Our Gut Microbes, But How Isn’t Yet Clear

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Ashley Yeager writes in The Scientist:

When Sara Campbell first typed “exercise and microbiome” into PubMed in 2010 and hit enter, “the search literally said zero,” she tells The Scientist. Campbell was just beginning an assistant professorship in exercise science at Rutgers University. Being an athlete herself and having studied cholesterol metabolism and exercise and diet during her PhD and postdoc, she started to wonder if exercise could influence the microbes in the gut.

“We know that exercise does all of these incredible things,” Campbell says, such as keeping inflammation down and enhancing antioxidant defenses. And so she thought, “well, if there’s symbiosis and mutualism that go on between the host and the microbes, there has to be something going on . . . something changing about the microbes” during exercise. When her PubMed search came up empty, she decided: “I’ve got to study this.”

Teaming up with microbiologists and toxicologists from Rutgers and a pathologist from Oklahoma City, Campbell designed an experiment to analyze fecal samples of male mice fed a normal or high-fat diet for 12 weeks. Some of the mice in each group were allowed to exercise, while the others remained sedentary. Physical activity, the results showed, generated a unique microbiome in the guts of the mice, independent of the animals’ diet: specifically, the mice that exercised hosted FaecalibacteriumClostridium, and Allobaculum, while the sedentary mice did not. The high-fat diet also caused inflammation in the guts of the sedentary mice, which was not seen in the mice that ate the fatty diet and exercised.

Published in March 2016, the results bolstered findings that came out a few years before showing that exercise prevented weight gain and altered the gut microbes in mice that became obese eating a high-fat diet. They also aligned nicely with a longitudinal study in humans published in 2018 that found lean, sedentary people who exercised for six weeks also developed higher levels of ClostridialesLachnospiraRoseburia, and Faecalibacterium in their guts, but those microbes returned to baseline levels when the individuals stopped exercising. Obese individuals who started exercising had changes to their gut microbes too, but those changes were different than what was seen in lean individuals.

While the reasons for the difference in changes between lean and obese individuals aren’t understood yet, the results make it clear that exercise, regardless of diet or body composition, change the gut microbiota of humans, says Jeffrey Woods, a researcher at the University of Illinois, Urbana-Champaign and a coauthor of the 2018 paper.

“This is a fairly new field in general and definitely a new field of exercise science,” he says, explaining that while the connection between exercise and gut microbe changes has been established, “how exercise changes the microbes, we do not know.” It’s also not yet clear whether the changes are beneficial to health, but there are clues that they might be.

Clues to the exercise-gut connection

One of the leading ideas in the field of exercise’s influence on the microbiome is that working out boosts the levels of gut microbes that produce butyrate—a short chain fatty acid that has a whole host of health benefits in humans, from producing satiety hormones that curb hunger to playing a role in supporting the survival of existing neurons and promoting the growth of new ones.

See “The Microbiome and Human Health

Faecalibacterium, along with other bacteria, such as Lachnospiraceae, that appear to increase in abundance in the gut after exercise, typically produce short chain fatty acids in response to the digestion of dietary fiber. In a review of animal and human experiments on physical activity and gut microbiome composition published in Exercise and Sport Science Reviews in April, Woods and colleagues propose that exercise might alter the gene expression of immune cells in the tissues of the gut, leading to the production of fewer pro-inflammatory cell-signaling proteins and more anti-inflammatory ones, as well as antioxidant enzymes. The immune cells sit near the microbial communities in the gut and could produce antimicrobial compounds that tamp down certain taxa while bolstering the growth of butyrate-producing bacteria. Exercise might also change the composition of mucus in the gut, which would affect bacterial species that live there, such as Akkermansia muciniphila—a bacterium with anti-inflammatory properties that appears to increase in abundance in response to exercise.

See “Commensal Bacterium Reduces ALS Symptoms in Mice

Exercise also raises a person’s core temperature and reduces blood flow to the intestines, which could lead to more direct contact between gut microbes and immune cells in the mucus of the gut—and has the potential to shift microbial composition. The circulation of bile acids, which can alter the microbial community of the gut, also increases during exercise, as does lactate, which might change the pH of the gut, shifting the diversity of the microbial community. “Those are some possible mechanisms we could test,” Woods says, “but they are not easy to test because it’s hard to isolate any one of them.”

Exercise, microbes, and bowel health

These potential mechanisms help explain some connections scientists have observed between the microbiome and bowel health. For example, colorectal cancer patients have a reduced abundance of butyrate-producing bacteria such as Roseburia and Lachnospiraceae. Butyrate in healthy cells spurs epigenetic modifications that lead to cell turnover and cell proliferation, while in colon cancer cells the fatty acids work through epigenetics to suppress cell proliferation and promote cell death, suggesting a benefit to colon cancer patients who exercise.

To measure the benefit of exercise against inflammation in the gut, Woods and colleagues performed the first  . . .

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Written by LeisureGuy

25 August 2019 at 1:16 pm

‘It’s a superpower’: how walking makes us healthier, happier and brainier

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Amy Fleming writes in the Guardian:

Taking a stroll with Shane O’Mara is a risky endeavour. The neuroscientist is so passionate about walking, and our collective right to go for walks, that he is determined not to let the slightest unfortunate aspect of urban design break his stride. So much so, that he has a habit of darting across busy roads as the lights change. “One of life’s great horrors as you’re walking is waiting for permission to cross the street,” he tells me, when we are forced to stop for traffic – a rude interruption when, as he says, “the experience of synchrony when walking together is one of life’s great pleasures”. He knows this not only through personal experience, but from cold, hard data – walking makes us healthier, happier and brainier.

We are wandering the streets of Dublin discussing O’Mara’s new book, In Praise of Walking, a backstage tour of what happens in our brains while we perambulate. Our jaunt begins at the grand old gates of his workplace, Trinity College, and takes in the Irish famine memorial at St Stephen’s Green, the Georgian mile, the birthplace of Francis Bacon, the site of Facebook’s new European mega-HQ and the salubrious seaside dwellings of Sandymount.

O’Mara, 53, is in his element striding through urban landscapes – from epic hikes across London’s sprawl to more sedate ambles in Oxford, where he received his DPhil – and waxing lyrical about science, nature, architecture and literature. He favours what he calls a “motor-centric” view of the brain – that it evolved to support movement and, therefore, if we stop moving about, it won’t work as well.

This is neatly illustrated by the life cycle of the humble sea squirt which, in its adult form, is a marine invertebrate found clinging to rocks or boat hulls. It has no brain because it has eaten it. During its larval stage, it had a backbone, a single eye and a basic brain to enable it to swim about hunting like “a small, water-dwelling, vertebrate cyclops”, as O’Mara puts it. The larval sea squirt knew when it was hungry and how to move about, and it could tell up from down. But, when it fused on to a rock to start its new vegetative existence, it consumed its redundant eye, brain and spinal cord. Certain species of jellyfish, conversely, start out as brainless polyps on rocks, only developing complicated nerves that might be considered semi-brains as they become swimmers.

Sitting at a desk all day, it’s easy to start feeling like a brainless polyp, whereas walking and talking, as we are this morning, while admiring the Great Sugar Loaf mountain rising beyond the city and a Huguenot cemetery formed in 1693, our minds are fizzing. “Our sensory systems work at their best when they’re moving about the world,” says O’Mara. He cites a 2018 study that tracked participants’ activity levels and personality traits over 20 years, and found that those who moved the least showed malign personality changes, scoring lower in the positive traits: openness, extraversion and agreeableness. There is substantial data showing that walkers have lower rates of depression, too. And we know, says O’Mara, “from the scientific literature, that getting people to engage in physical activity before they engage in a creative act is very powerful. My notion – and we need to test this – is that the activation that occurs across the whole of the brain during problem-solving becomes much greater almost as an accident of walking demanding lots of neural resources.”

O’Mara’s enthusiasm for walking ties in with both of his main interests as a professor of experimental brain research: stress, depression and anxiety; and learning, memory and cognition. “It turns out that the brain systems that support learning, memory and cognition are the same ones that are very badly affected by stress and depression,” he says. “And by a quirk of evolution, these brain systems also support functions such as cognitive mapping,” by which he means our internal GPS system. But these aren’t the only overlaps between movement and mental and cognitive health that neuroscience has identified.

I witnessed the brain-healing effects of walking when my partner was recovering from an acute brain injury. His mind was often unsettled, but during our evening strolls through east London, things started to make more sense and conversation flowed easily. O’Mara nods knowingly. “You’re walking rhythmically together,” he says, “and there are all sorts of rhythms happening in the brain as a result of engaging in that kind of activity, and they’re absent when you’re sitting. One of the great overlooked superpowers we have is that, when we get up and walk, our senses are sharpened. Rhythms that would previously be quiet suddenly come to life, and the way our brain interacts with our body changes.”

From the scant data available on walking and brain injury, says O’Mara, “it is reasonable to surmise that supervised walking may help with acquired brain injury, depending on the nature, type and extent of injury – perhaps by promoting blood flow, and perhaps also through the effect of entraining various electrical rhythms in the brain. And perhaps by engaging in systematic dual tasking, such as talking and walking.”

One such rhythm, he says, is that of theta brainwaves. Theta is a pulse or frequency (seven to eight hertz, to be precise) which, says O’Mara, “you can detect all over the brain during the course of movement, and it has all sorts of wonderful effects in terms of assisting learning and memory, and those kinds of things”. Theta cranks up when we move around because it is needed for spatial learning, and O’Mara suspects that walking is the best movement for such learning. “The timescales that walking affords us are the ones we evolved with,” he writes, “and in which information pickup from the environment most easily occurs.”

Essential brain-nourishing molecules are produced by aerobically demanding activity, too. You’ll get raised levels of brain-derived neurotrophic factor (BDNF) which, writes O’Mara, “could be thought of as a kind of a molecular fertiliser produced within the brain because it supports structural remodelling and growth of synapses after learning … BDNF increases resilience to ageing, and damage caused by trauma or infection.” Then there’s vascular endothelial growth factor (VEGF), which helps to grow the network of blood vessels carrying oxygen and nutrients to brain cells.

Some people, I point out, don’t think walking counts as proper exercise. “This is a terrible mistake,” he says. “What we need to be is much more generally active over the course of the day than we are.” And often, an hour at the gym doesn’t cut it. “What you see if you get people to wear activity monitors is that because they engage in an hour of really intense activity, they engage in much less activity afterwards.” . . .

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Written by LeisureGuy

2 August 2019 at 9:24 am

The Island Where People Forget to Die

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This is a golden oldie (from October 24, 2012) that is of new interest with my whole-food plant-based diet. Thanks to Joanne VR for pointing it out. Dan Buettner wrote in the NY Times Magazine:

In 1943, a Greek war veteran named Stamatis Moraitis came to the United States for treatment of a combat-mangled arm. He’d survived a gunshot wound, escaped to Turkey and eventually talked his way onto the Queen Elizabeth, then serving as a troopship, to cross the Atlantic. Moraitis settled in Port Jefferson, N.Y., an enclave of countrymen from his native island, Ikaria. He quickly landed a job doing manual labor. Later, he moved to Boynton Beach, Fla. Along the way, Moraitis married a Greek-American woman, had three children and bought a three-bedroom house and a 1951 Chevrolet.

One day in 1976, Moraitis felt short of breath. Climbing stairs was a chore; he had to quit working midday. After X-rays, his doctor concluded that Moraitis had lung cancer. As he recalls, nine other doctors confirmed the diagnosis. They gave him nine months to live. He was in his mid-60s.

Moraitis considered staying in America and seeking aggressive cancer treatment at a local hospital. That way, he could also be close to his adult children. But he decided instead to return to Ikaria, where he could be buried with his ancestors in a cemetery shaded by oak trees that overlooked the Aegean Sea. He figured a funeral in the United States would cost thousands, a traditional Ikarian one only $200, leaving more of his retirement savings for his wife, Elpiniki. Moraitis and Elpiniki moved in with his elderly parents, into a tiny, whitewashed house on two acres of stepped vineyards near Evdilos, on the north side of Ikaria. At first, he spent his days in bed, as his mother and wife tended to him. He reconnected with his faith. On Sunday mornings, he hobbled up the hill to a tiny Greek Orthodox chapel where his grandfather once served as a priest. When his childhood friends discovered that he had moved back, they started showing up every afternoon. They’d talk for hours, an activity that invariably involved a bottle or two of locally produced wine. I might as well die happy, he thought.

In the ensuing months, something strange happened. He says he started to feel stronger. One day, feeling ambitious, he planted some vegetables in the garden. He didn’t expect to live to harvest them, but he enjoyed being in the sunshine, breathing the ocean air. Elpiniki could enjoy the fresh vegetables after he was gone.

Six months came and went. Moraitis didn’t die. Instead, he reaped his garden and, feeling emboldened, cleaned up the family vineyard as well. Easing himself into the island routine, he woke up when he felt like it, worked in the vineyards until midafternoon, made himself lunch and then took a long nap. In the evenings, he often walked to the local tavern, where he played dominoes past midnight. The years passed. His health continued to improve. He added a couple of rooms to his parents’ home so his children could visit. He built up the vineyard until it produced 400 gallons of wine a year. Today, three and a half decades later, he’s 97 years old — according to an official document he disputes; he says he’s 102 — and cancer-free. He never went through chemotherapy, took drugs or sought therapy of any sort. All he did was move home to Ikaria.

I met Moraitis on Ikaria this past July during one of my visits to explore the extraordinary longevity of the island’s residents. For a decade, with support from the National Geographic Society, I’ve been organizing a study of the places where people live longest. The project grew out of studies by my partners, Dr. Gianni Pes of the University of Sassari in Italy and Dr. Michel Poulain, a Belgian demographer. In 2000, they identified a region of Sardinia’s Nuoro province as the place with the highest concentration of male centenarians in the world. As they zeroed in on a cluster of villages high in Nuoro’s mountains, they drew a boundary in blue ink on a map and began referring to the area inside as the “blue zone.” Starting in 2002, we identified three other populations around the world where people live measurably longer lives than everyone else. The world’s longest-lived women are found on the island of Okinawa. On Costa Rica’s Nicoya Peninsula, we discovered a population of 100,000 mestizos with a lower-than-normal rate of middle-age mortality. And in Loma Linda, Calif., we identified a population of Seventh-day Adventists in which most of the adherents’ life expectancy exceeded the American average by about a decade.

In 2003, I started a consulting firm to see if it was possible to take what we were learning in the field and apply it to American communities. We also continued to do research and look for other pockets of longevity, and in 2008, following a lead from a Greek researcher, we began investigating Ikaria. Poulain’s plan there was to track down survivors born between 1900 and 1920 and determine when and where individuals died. The approach was complicated by the fact that people often moved around. That meant that not only were birth and death records required, but also information on immigration and emigration.

The data collection had to be rigorous. Earlier claims about long-lived people in places like Ecuador’s Vilcabamba Valley, Pakistan’s Hunza Valley or the Caucasus Mountains of Georgia had all been debunked after researchers discovered that many residents didn’t actually know their ages. For villagers born without birth certificates, it was easy to lose track. One year they were 80; a few months later they were 82. Pretty soon they claimed to be 100. And when a town discovers that a reputation for centenarians draws tourists, who’s going to question it? Even in Ikaria, the truth has been sometimes difficult to nail down. Stories like the one about Moraitis’s miraculous recovery become instant folklore, told and retold and changed and misattributed. (Stories about Moraitis have appeared on Greek TV.) In fact, when I was doing research there in 2009, I met a different man who told me virtually the exact same story about himself.

The study would try to cut through the stories and establish the facts about Ikaria’s longevity. Before including subjects, Poulain cross-referenced birth records against baptism or military documentation. After gathering all the data, he and his colleagues at the University of Athens concluded that people on Ikaria were, in fact, reaching the age of 90 at two and a half times the rate Americans do. (Ikarian men in particular are nearly four times as likely as their American counterparts to reach 90, often in better health.) But more than that, they were also living about 8 to 10 years longer before succumbing to cancers and cardiovascular disease, and they suffered less depression and about a quarter the rate of dementia. Almost half of Americans 85 and older show signs of Alzheimer’s. (The Alzheimer’s Association estimates that dementia cost Americans some $200 billion in 2012.) On Ikaria, however, people have been managing to stay sharp to the end.

Ikaria, an island of 99 square miles and home to almost 10,000 Greek nationals, lies about 30 miles off the western coast of Turkey. Its jagged ridge of scrub-covered mountains rises steeply out of the Aegean Sea. Before the Christian era, the island was home to thick oak forests and productive vineyards. Its reputation as a health destination dates back 25 centuries, when Greeks traveled to the island to soak in the hot springs near Therma. In the 17th century, Joseph Georgirenes, the bishop of Ikaria, described its residents as proud people who slept on the ground. “The most commendable thing on this island,” he wrote, “is their air and water, both so healthful that people are very long-lived, it being an ordinary thing to see persons in it of 100 years of age.”

Seeking to learn more about the island’s reputation for long-lived residents, I called on Dr. Ilias Leriadis, one of Ikaria’s few physicians, in 2009. On an outdoor patio at his weekend house, he set a table with Kalamata olives, hummus, heavy Ikarian bread and wine. “People stay up late here,” Leriadis said. . .

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Written by LeisureGuy

11 July 2019 at 8:13 am

Good dietary analysis program: Cronometer.com

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I just learned about Cronometer.com: it’s free, and it includes an analysis of your micronutrient intake (and goals). Worth entering a day’s food from time to time and see how you’re doing.

The breakdown has color bars that show what percentage of the recommended amount of each micronutrient you’re getting. If you hover the mouse over the color bar, a popup shows the contribution from each of the foods you entered sorted in descending order on amount.

Also, if you highlight (click on) one of the foods you entered, you get the analysis just for that food.

And you can drag and drop the foods you’ve entered to reorder them.

Written by LeisureGuy

8 June 2019 at 8:50 am

Even One Extra Walk a Day May Make a Big Difference

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I’m back to doing Nordic walking, and The Younger Daughter pointed out this NY Times article by Gretchen Reynolds:

How many steps should people take every day for good health?

A new study of activity and mortality in older women finds that the total could be lower than many of us expect and that even small increases in steps can be meaningful. The study also side-eyes the validity, utility and origin of the common 10,000-step-a-day exercise goals built into so many of our phones and activity monitors and suggests, instead, that any moving, whether or not it counts as exercise, may help to extend people’s lives.

By now, almost all of us know that walking and other types of physical activity are indispensable to our well-being. Studies show that active people have lower incidences of heart disease, obesity and Type 2 diabetes and usually live longer than people who are sedentary. But many of us remain confused about just how much exercise we need and how intense it should be.

The official exercise guidelines in the United States and many other nations recommend that adults complete at least 150 minutes a week of moderate exercise, such as walking. These guidelines are based, for the most part, on past studies linking the length of time people are active with their subsequent robust or poor health.

But some scientists have begun to suspect that telling people to measure their workouts in minutes may not be ideal.

“People may not intuitively grasp what 150 minutes a week of exercise means in practical terms,” says I-Min Lee, a professor of medicine at Harvard University, who led the new study.

Step counts are a simpler, more concrete and convenient measure of physical activity, she says. We can understand the concept of a step and how to add them up. And, helpfully, many of us possess technology in our phones or activity monitors that will count our steps for us.

But few past studies have correlated steps and health, largely because such research requires people to wear activity monitors and not just tell researchers how often they exercise.

So, for the new study, which was published last week in JAMA Internal Medicine, Dr. Lee and her colleagues set out to objectively quantify how many steps might be needed to avoid premature mortality.

Many of us likely assume that the answer is 10,000, since so many of our activity monitors use that threshold as a goal. But no scientific evidence supports that idea, Dr. Lee says. The concept of 10,000 steps seems to have originated, in fact, with a Japanese clock maker in the 1960s, she says. It gave its consumer pedometer a Japanese name that translates as “10,000 steps,” and somehow that ideal took hold. (Some past research suggests that we might need to take more than 10,000 steps to protect ourselves against heart disease.)

Now, aiming instead to use science rather than semantics, Dr. Lee and her colleagues began trolling through the massive data from the Women’s Health Study, which has been tracking the health and habits of older women for decades.

As part of that study, thousands of older women had worn a sophisticated activity monitor for a week. It tracked the steps each woman took per minute throughout the day (but without showing any readout of the totals, so the women would not know or respond to the counts).

The women also provided information to the researchers about their overall health and lifestyles.

The researchers gathered the step-count and health data from almost 17,000 of the participants, most of them in their 70s, and none of whom reported poor health. The scientists also checked death records for the subsequent four to five years and then compared step counts and mortality.

Those comparisons proved to be telling. The women who had moved the least, taking only about 2,700 steps a day, were the most likely to have died during the follow-up period. Women who moved more often had considerably less risk of premature death, up to a plateau of about 7,500 steps a day.

Meanwhile, the sweet spot for reducing the risk of premature death was about 4,500 steps per day, the data showed. A woman who reached that threshold was about 40 percent less likely to have died during the follow-up period than someone taking about 2,700 steps each day.

“We were quite surprised that such a relatively small number of steps would be associated with such a substantial reduction in mortality,” Dr. Lee says.

The data also indicated that few of the women walked intensively; for the most part, they strolled, rather than rushed. Few walked for exercise. But intensity did not matter in this study. Only the number of steps per day was associated with mortality, not the speed with which the women accumulated them. . .

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Written by LeisureGuy

8 June 2019 at 8:37 am

Regarding cardio exercise and brain function

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Also from How Not to Die, by Michael Greger MD:

In a 2010 study published in the Archives of Neurology, researchers took a group of people with mild cognitive impairment—those who are starting to forget things, for example, or regularly repeating themselves—and had them engage in aerobic exercise for forty-five to sixty minutes a day, four days a week, for six months. The control group was instructed to simply stretch for the same time periods.

Memory tests were performed before and after the study. Researchers found that in the control (stretching) group, cognitive function continued to decline. But the exercising group not only didn’t get worse, they got better. The exercisers got more test answers correct after six months, indicating their memory had improved.

Subsequent studies using MRI scans found that aerobic exercise can actually reverse age-related shrinkage in the memory centers of the brain. No such effect was found in the stretching and toning control groups or a nonaerobic strength-training group. Aerobic exercise can help improve cerebral blood flow, improve memory performance, and help preserve brain tissue.

Written by LeisureGuy

19 May 2019 at 2:32 pm

Exercise reduces chronic inflammation

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And why is that important? From an article in Harvard Magazine:

Because the idea that inflammation—constant, low-level, immune-system activation —could be at the root of many noncommunicable diseases is a startling claim, it requires extraordinary proof. Can seemingly unconnected illnesses of the brain, the vasculature, lungs, liver, and joints really share a deep biological link? Evidence has been mounting that these common chronic conditions—including Alzheimer’s, cancer, arthritis, asthma, gout, psoriasis, anemia, Parkinson’s disease, multiple sclerosis, diabetes, and depression among them—are indeed triggered by low-grade, long-term inflammation. But it took that large-scale human clinical trial to dispel any lingering doubt: the immune system’s inflammatory response is killing people by degrees.

 

Written by LeisureGuy

26 April 2019 at 1:19 pm

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